1. Field of the Invention
The present invention relates to a working system for circuit boards such as a mounting apparatus for mounting electronic components on a circuit board, a printing machine for printing solder on a circuit board, an adhesive applying machine for applying adhesive on a circuit board, and the like.
2. Discussion of the Related Art
Heretofore, a working system for circuit boards uses circuit board transfer means for transferring circuit boards into and from the system, and as the transfer means, there has been known one which positions each circuit board upon engagement with a stop. A technology has been in existence for reducing the circuit board transfer speed from a high speed to a low speed to absorb the shock upon engagement with the stop, and another technology has also been in existence for detecting whether or not the circuit board is present at a predetermined position when stopped.
For example, Japanese Unexamined Published Patent Application No. 11-163595 (the equivalent thereto: U.S. Pat. No. 6,189,674 B1) discloses a stop for positioning a circuit board to a target position, a positioning detector for detecting the engagement of the circuit board with the stop and an arrival detector for detecting the arrival of the circuit board at a predetermined position which is between a transfer start position from which the circuit board begins to start and a target position at which the transfer is to be terminated and further discloses the provision of a function of outputting a deceleration signal to a drive device in response to a detection signal from the arrival detector. That is, there are disclosed a technology for judging the presence of the circuit board at the predetermined position in dependence on the positioning detector and another technology for decelerating the board transfer speed from the high speed to the low speed to absorb the shock upon engagement with the stop in dependence on the arrival detector and in accordance with the deceleration signal output function.
However, the prior art requires dedicated sensors which respectively serve as the positioning detector and the arrival detector and thus, gives rise to a problem that the provision of such dedicated sensors causes the working system for circuit boards to be increased in manufacturing cost. Further, since it is often the case that a back surface is used to support the circuit board at a working position in the working system, the existence of the arrival detector in the case makes it difficult to provide a support mechanism for the circuit board around the arrival detector.